Insulation gas filled tubular casing structure for high voltage conductor

ABSTRACT

A high-voltage tubular electrical conductor is encapsulated within an insulation gas filled rectilinear tubular casing and supported centrally within the casing by longitudinally spaced support-insulators each of which is provided with three legs spaced 120* apart about the conductor. Two of the legs are fixedly secured to the conductor structure and include rolling means in the form of balls at their outer ends to facilitate abrasion-free insertion of the conductor-support insulator assembly within the casing. The third leg is supported by the tubular conductor for movement in a radial direction by a drive mechanism to enable the leg to be moved from radially inward position establishing an initial clearance with the wall of the casing during insertion of the conductor and support insulator assembly to a radially outward position establishing a springloaded elastic pressure contact with the casing wall thereby to secure the support-insulator in position against longitudinal displacement. The drive mechanism for the radially displaceable leg is a tapered screw which, when rotated by a key inserted through the conductor, advances the tapered drive sur-face longitudinally and forces the leg radially outward.

United States Patent 1191 Floessel June 12, 1973 [5 INSULATIONGAS-FILLED TUBULAR Primary Examiner-Bernard A. Gilheany CASING STRUCTUREFOR HIGH-VOLTAGE Assistant ExaminerA. T. Grimley CONDUCTOR A tt0rneyPierce, Scheffler and Parker [75] Inventor: Dieter Floessel, Fislisbach,

Switzerland [57] ABSTRACT Assigneei Aktiengeseuschlifl Brow", Boveri & Ahigh-voltage tubular electrical conductor is encapsu- Baden, Switzerlandlated within an insulation gas filled rectilinear tubular [22] Fied;June 13 1972 casing and supported centrally within the casing bylongitudinally spaced support-insulators each of which is 1 1 PP 262,174provided with three legs spaced 120 apart about the conductor. Two ofthe legs are fixedly secured to the [30] Foreign Application PriorityData conductor structure and include rolling means in the S t 16 1971 Sr] d 13539! form of balls at their outer ends to facilitate abrasione anfree insertion of the conductor-support insulator as- U S Cl 174/28174/16 B 1.74/99 B sembly within the casing. The third leg is supportedby i 9/06 the tubular conductor for movement in a radial direction y adrive mechanism to enable the g to be [58] Q Z 31%; moved from radiallyinward position establishing an inill 121 tial clearance with the wallof the casing during insertion of the conductor and support insulatorassembly to a radially outward position establishing a spring-loaded[56] References cued elastic pressure contact with the casing wallthereby to UNITED STATES PATENTS secure the support-insulator inposition against longitu- 3,688,015 8/1972 Graybill 174/16 B dinaldisplacement, The drive mechanism for the radi- 3,221,097 11/ 1965Cognet 174/99 B ally displaceable leg is a tapered screw which, when ro-2,355,111 8/1328 Rouault 174/28 med by a key inserted through theConductor, 49 934 3:33;: vances the tapered drive sur-facelongitudinally and 1:935:313 11/1933 Feldman 174/28 the leg manyoutward- FOREIGN PATENTS OR APPLICATIONS 6 Claims, 3 Drawing Figures879,601 3/1943 France 174/28 I I f 1 I 2 3a m 3 9 5a 8 2 7 6b3b6 6 1oPATENTE JUN 1 2191s SHEET 2 0F 2 a P 1E 1 INSULATION GAS-FILLED TUBULARCASING STRUCTURE FOR HIGH-VOLTAGE CONDUCTOR The present inventionrelates to an improvement in the construction of insulation gas-filledtubular encased i.e. encapsulated high-voltage electrical conductors.More particularly, the invention concerns an enclosed high-voltageconductor of the general type wherein the conductor is held in placecentrally within a rectilinear, grounded metallic casing by means ofsupport insulators which are spaced longitudinally along the conductor.

Enclosed high-voltage conductor structures of this type are known to theindustry, reference being made, for example, to the disclosure in U.S.Pat. No. 2,428,051 wherein the conductor is supported by three legsuniformly spaced about the conductor, i.e. 120

apart in the same plane, and which extend radially into engagement withthe inner wall surface of the cylindrical enclosing casing structure.The inner ends of the legs are screwed to the conductor and the outerends are provided with spring means which enable the legs to bemaintained in place by spring-loaded frictional contact with the innerwall surface of the casing. This construction, however, suffers from thedisadvantage that when the insulator-conductor structure is insertedwithin the casing, a certain amount of abrading unavoidably takes placeas the spring components slide under radial pressure along the innerwall surface of the casing with the result that small bits and chips ofmetal collect within the casing. However, without an exceedingly highcost, it is impossible to remove all of such impurities from theinterior of the casing, with the result that the electrical stability ofthe high-voltage line is adversely affected.

The principal objective of the present invention is to provide animproved multi-leg support insulator construction for encasedhigh-voltage conductors which avoids the disadvantages of the priorknown constructions and which enables the multi-leg support to beinserted into the enclosing casing without any abrading effect. Theobjective isattained in that an initial clearance is provided betweenthe multi-leg support and the inner wall of the casing to permitabrasion-free insertion of the support to its appointed location withinthe casing, following which at least one leg of the multi-leg support isexpanded radially to engage the inner wall of the casing and developapressurized, holding contact between the support and casing. Moreparticularly, the pressurized holding contact between the muIti-legsupport and casing is established by a tapered-screw drive locatedwithin the conductor, which latter has a tubular configuration, thetapered drive being advanced longitudinally within the conductor as itis rotated by a suitable tool and causing the inner end of one leg ofthe support, which is mounted for radial movement in the wall of theconductor, and which is engaged by the tapered surface of the drive, tobe displaced in the radial direction to engage the inner wall of thecasing. As a further feature of the invention, the tapered-screw driveis mounted within 'an internally threaded nipple interconnecting theends of two conductor sections joined together by the nipple.

The foregoing as well as other objects and advantages inherent in theimproved encapsulated conductor structure will become more apparent fromthe following description of a preferred embodiment thereof and from theaccompanying drawings wherein:

FIG. 1 is a transverse section through the encapsulated conductor in thevicinity of the insulator support structure; and

FIGS. 2 and 3 are views in diametral section of the encapsulatedconductor showing the details of the tapcred-screw drive and legs of thesupport insulator, FIG. 2 depicting the radially driven leg in itsholding position against the inner wall of the casing, and FIG. 3depicting the radially driven leg in the initial loosened position,clearing the wall of the casing.

With reference now to the drawings, wherein corresponding referencenumerals are used for corresponding structural components in allfigures, the encapsulated conductor structure includes a rectilinearcylindrical tubular casing l which preferably is made from aluminum andearthed as indicated by the conventional symbol. Located centrallywithin the casing l is the high-voltage conductor structure consistingof cylindrical tubular conductor sections 2, 2 which are joined togetherby a tubular coupling nipple 3. The opposite ends of the nipple areprovided with portions of reduced diameter which are inserted within theends of the conductor sections 2, 2 and welded thereto by circular welds10.

The multi-leg insulator support structure for the conductor consists ofthree legs 4, 4 and 5 spaced apart around the conductor and which arelocated in the same plane. As depicted in FIG. 2, each of the two legs4, 4 is provided at its inner end with a foot portion 4b of reducedcross-section which is inserted in an opening 3b innipple 3 having acomplementary configuration and secured thereto by any suitable meanssuch as an adhesive. The outer end of each leg 4, 4 is provided with ananti-friction rolling means such as balls 40 made from metal or plastic.During installation of the conductor-support insulator assembly withincasing 1, these roll means 4a at the outer ends of the two legs 4, 4ensure easy and abrasion-free relative longitudinal movement between thecasing and the conductorsupport insulator assembly, there being at suchtime a clearance 5a between the third leg 5 and the casing wall, asdepicted in FIG. 3.

As previously indicated, this third leg 5 is mounted for movement in aradial direction and is actuated by a tapered-screw drive. To this end,a cup-shaped part 8 is mounted for sliding movement within an opening 30in nipple 3, and inserted into the outer open end of the cup 8 is theinner end 5a of the leg 5 and which has a reduced cross section. Cupsprings 9 surround the inner end 5a of leg 5 and provide an elasticallyyieldable drive between cup 8 and leg 5. The inner end of cup 8 engagesthe inner tapered end 6a of a drive member 6 which is externallythreaded at 6b at its opposite end to establish a screw engagement withan internally threaded part 3a of the conductor nipple 3. In order toeffect rotation of drive member 6, the end wall at the threaded end 6bthereof is provided with a noncircular, e.g. rectangular opening 7 toreceive-the complementarily configured end 10a of a key 10 inserted intothe hollow conductor 2 and which is guided longitudinally withinconductor 2 by a cylindrical collar 10b thereon slightly smaller indiameter than the internal diameter of the conductor.

As previously explained, the assembly of conductor structure 2, 3, 2 andits related tri-leg insulator support 4, 4, are located with theencapsulating casing 1 by a sliding movement therebetween, in which theballs 4a on the two legs 4, 4 rollingly glide along the inner wall ofthe casing to the proper position, the third leg 5 being in its radiallyinward position as depicted in FIG. 7

3 to develop a clearance 5b between the outer end thereof and the casingwall. Upon reaching the proper position within casing 1, key 10, withits end a inserted into the opening 7 in drive member 6 is then rotatedthus effecting a longitudinal advance of drive member 6 to the right, asviewed in FIG. 2, accompanied by radially outward displacement of cup 8and leg 5 as cup 8 moves upwardly along the taper 6a; Cup 8 impartsmovement to leg 5 indirectly by way of the cup springs 9 which serve twofunctions. One function is to prevent excessive radial pressure by thelegs 4, 4, 5 upon casing l which otherwise could lead to deformations ofthe casing at the three points of contact with the legs; secondly, andmost important, these springs provide compensation for an expansion orcontraction of the casing and support insulator which may arise, forexample, as a result of a change in temperature.

In accordance with standard procedure, the interior of casing 1 isfilled with an insulating gas such as, for example, SF pressurized to apressure of about 4 atmospheres. Finally, it will be understood that theconductor structure is supported within its casing by a number of theinsulator supports constructed in accordance with the invention, andspaced along the conductor at the desired intervals. However, in orderto simplify the drawings, only one of the conductor supports and therelated portion of the casing have been included.

I claim:

1. An encapsulated gas-filled high-voltage electrical conductorstructure comprising a rectilinear tubular metallic gas-filled casing, arectilinear electrical conductor extending longitudinally within saidcasing, and at least one support insulator structure for centering saidconductor within said casing and securing it against longitudinaldisplacement therein, said support insulator structure comprising atleast three legs mounted on said conductor and extending radially indifferent directions therefrom in a common plane, the outer ends of aplurality of said legs secured to said conductor in fixed position beingprovided with rolling means to facilitate abrasion-free insertion of theconductor-support insulator assembly within said casing in rollingcontact with the inner wall thereof, and at least another one of saidlegs being movable in the radial direction and including drive meanstherefor providing leg movement from a radially inward positionestablishing an initial clearance between its outer end and the innerwall of said casing to a radially outward position following insertionof said conductor-support insulator assembly and establishing apressurized contact with the inner wall of said casing thereby to securesaid conductor-support insulator assembly against longitudinaldisplacement within said casing.

2. An encapsulated insulation gas-filled high-voltage electricalconductor structure comprising a rectilinear tubular metallic gas-filledcasing, a rectilinear tubular electrical conductor extendinglongitudinally within said casing, and at least one support insulatorstructure for centering said conductor within said casing and securingit against longitudinal displacement therein, said support insulatorstructure comprising three legs mounted on said conductor and extendingradially in different directions therefrom in a common plane, the outerends of two of said legs secured to said conductor in fixed positionbeing provided with rolling means to facilitate abrasion-free insertionof the conductorsupport insulator assembly within said casing in rollingcontact with the inner wall thereof, and the third leg being mounted onsaid conductor for movement in a radial direction and including atapered screw drive located within said conductor providing movement ofsaid third leg from a radially inward position establishing an initialclearance between its outer end and the inner wall of said casing to aradially outward position following insertion of said conductor-supportinsulator assembly and establishing a pressurized contact with the innerwall of said casing thereby to secure said conductor-support insulatorassembly against longitudinal displacement within said casing.

3. An encapsulated insulation gas-filled high-voltage electricalconductor structure as defined in claim 2 wherein the inner end portionof said radially movable third leg is reduced in cross-section and isreceived in a cup member which extends through an opening in the wall ofsaid conductor to engage the tapered surface of said tapered screwdrive, and spring means are provided in the connection between said cupmember and said third leg through which the radially outward force isapplied to said third leg thereby providing a yieldable connectiontherebetween to accommodate temperature-induced expansion or contractionof said casing.

4. An encapsulated insulation gas-filled high-voltage electricalconductor structure as defined in claim 3 wherein said spring means areconstituted by cup springs which surround said end portion of reducedcross-section.

5. An encapsulated insulation gas-filled high-voltage electricalconductor structure as defined in claim 3 wherein the tapered screwcomponent of said drive includes a non-circular opening for receivingthe complementarily configured end of a tool inserted through saidtubular conductor for effecting rotation of said tapered screw and thesimultaneous longitudinal advance thereof.

6. An encapsulated insulation gas-filled highvoltage electricalconductor structure as defined in claim 3 wherein the three legs of saidsupport insulator structure are mounted on a tubular conductive nippleinterconnecting the ends of adjacent tubular conductor sections, saidnipple being internally threaded to engage external threads provided onsaid tapered screw, said tapered screw component being provided with anoncircular opening for receiving the complementarily configured end ofa tool inserted through said tubular conductor section and nipple foreffecting rotation of said tapered screw and the simultaneouslongitudinal advance thereof, and said tubular nipple being providedwith an opening in the wall thereof and through which said cup memberextends to engage the tapered surface of said screw.

1. An encapsulated gas-filled high-voltage electrical conductorstructure comprising a rectilinear tubular metallic gas-filled casing, arectilinear electrical conductor extending longitudinally within saidcasing, and at least one support insulator structure for centering saidconductor within said casing and securing it against longitudinaldisplacement therein, said support insulator structure comprising atleast three legs mounted on said conductor and extending radially indifferent directions therefrom in a common plane, the outer ends of aplurality of said legs secured to said conductor in fixed position beingprovided with rolling means to facilitate abrasion-free insertion of theconductor-support insulator assembly within said casing in rollingcontact with the inner wall thereof, and at least another one of saidlegs being movable in the radial direction and including drive meanstherefor providing leg movement from a radially inward positionestablishing an initial clearance between its outer end and the innerwall of said casing to a radially outward position following insertionof said conductor-support insulator assembly and establishing apressurized contact with the inner wall of said casing thereby to securesaid conductor-support insulator assembly against longitudinaldisplacement within said casing.
 2. An encapsulated insulaTiongas-filled high-voltage electrical conductor structure comprising arectilinear tubular metallic gas-filled casing, a rectilinear tubularelectrical conductor extending longitudinally within said casing, and atleast one support insulator structure for centering said conductorwithin said casing and securing it against longitudinal displacementtherein, said support insulator structure comprising three legs mountedon said conductor and extending radially in different directionstherefrom in a common plane, the outer ends of two of said legs securedto said conductor in fixed position being provided with rolling means tofacilitate abrasion-free insertion of the conductor-support insulatorassembly within said casing in rolling contact with the inner wallthereof, and the third leg being mounted on said conductor for movementin a radial direction and including a tapered screw drive located withinsaid conductor providing movement of said third leg from a radiallyinward position establishing an initial clearance between its outer endand the inner wall of said casing to a radially outward positionfollowing insertion of said conductor-support insulator assembly andestablishing a pressurized contact with the inner wall of said casingthereby to secure said conductor-support insulator assembly againstlongitudinal displacement within said casing.
 3. An encapsulatedinsulation gas-filled high-voltage electrical conductor structure asdefined in claim 2 wherein the inner end portion of said radiallymovable third leg is reduced in cross-section and is received in a cupmember which extends through an opening in the wall of said conductor toengage the tapered surface of said tapered screw drive, and spring meansare provided in the connection between said cup member and said thirdleg through which the radially outward force is applied to said thirdleg thereby providing a yieldable connection therebetween to accommodatetemperature-induced expansion or contraction of said casing.
 4. Anencapsulated insulation gas-filled high-voltage electrical conductorstructure as defined in claim 3 wherein said spring means areconstituted by cup springs which surround said end portion of reducedcross-section.
 5. An encapsulated insulation gas-filled high-voltageelectrical conductor structure as defined in claim 3 wherein the taperedscrew component of said drive includes a non-circular opening forreceiving the complementarily configured end of a tool inserted throughsaid tubular conductor for effecting rotation of said tapered screw andthe simultaneous longitudinal advance thereof.
 6. An encapsulatedinsulation gas-filled high-voltage electrical conductor structure asdefined in claim 3 wherein the three legs of said support insulatorstructure are mounted on a tubular conductive nipple interconnecting theends of adjacent tubular conductor sections, said nipple beinginternally threaded to engage external threads provided on said taperedscrew, said tapered screw component being provided with a non-circularopening for receiving the complementarily configured end of a toolinserted through said tubular conductor section and nipple for effectingrotation of said tapered screw and the simultaneous longitudinal advancethereof, and said tubular nipple being provided with an opening in thewall thereof and through which said cup member extends to engage thetapered surface of said screw.